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The CDC now recommends that high-risk infants undergo postvaccination serologic testing between 9 and 12 months, updated from 9-18 months. The new vaccination interval can better cover at risk infants from HBV infection and also help ensure a higher adherence to the immunoprophylaxis protocol.
New data from the Centers for Disease Control and Prevention (CDC) suggests that postvaccination serologic testing should be performed in infants born to hepatitis B-infected mothers between 9 and 12 months of age, instead of between 9 and 18 months as previously recommended.
Postvaccination serologic testing (PVST) assesses an infant’s response to hepatitis B virus (HBV) vaccination, and the shortened PVST timeline was newly recommended following the results of a recent study1 from the CDC. The study of 8105 infants found that after shortening the interval to 1-2 months after the final dose, which would generally correspond to testing at 9 to 12 months of age, 2% of the infants tested had levels of antibodies to hepatitis B surface antigen (anti-HBsAg) of less than 10 mIU/mL. By 7 to 8 months postvaccination, the proportion increased to 8%.
“Performing PVST at 9 to 12 months of life enables the possibility of a prompt revaccination of those infants who require revaccination with a second 3-dose HBV vaccine series in order to achieve adequate protective antibody levels,” said Sarah Schillie, MD, a medical epidemiologist in the Division of Viral Hepatitis at the CDC in Atlanta, Georgia, and main author of the study.
Another reason that prompted the new PVST recommendation was the discontinuation of the Haemophilus b Conjugate (Meningococcal Protein Conjugate) and Hepatitis B (Recombinant) Vaccine (COMVAX) vaccine. According to Dr Schillie, infants receiving the COMVAX vaccine did not complete their vaccine series until aged about 15 months, necessitating the extension of the interval of PVST up to 18 months to accommodate those infants completing their vaccination series with COMVAX.
“In addition, the new data shows that surface antibody, which is a measure of vaccine response, declines over time following vaccination, although infants are still protected,” said Dr Schillie. “What was happening is that infants were getting revaccinated unnecessarily and these new guidelines correct that.”
Perinatal exposure is an important mode of HBV transmission, resulting in chronic disease in approximately 90% of infected infants, Dr Schillie said, underscoring the urgency for an effective and timely immunoprophylaxis in high-risk infants.
“Preventing perinatal HBV transmission is a critical part of the national strategy to eliminate HBV infection in the United States,” she stated. “It is important for healthcare providers to understand that HBV in pregnant women poses a serious risk for chronic HBV infection, liver failure, as well as hepatocellular carcinoma in their infants.”
The current recommendations of immunoprophylaxis in high-risk infants consist of the administration of hepatitis B vaccine and hepatitis B immune globulin within 12 hours of birth, and completion of the 3-dose hepatitis B vaccine series. According to Dr Schillie, this cornerstone approach of immunoprophylaxis for perinatal HBV prevention is extremely effective and can reduce up to 95% of perinatal HBV infections.
“We need to ensure that all infants at risk receive their immunoprophylaxis for hepatitis B [in a timely manner] and that patients are compliant with the new guidelines here,” Dr. Schillie explained. “However, despite a timely immunoprophylaxis, there will still be a very small percentage of babies who do get infected and, most often, those babies are probably born to mothers who have high viral loads.”
Other factors that are associated with an increased risk of infection in infants include those born to mothers who are younger, who are of Asian/Pacific Islander ancestry, who are HBV e-antigen positive. Also at risk are those infants who receive fewer than 3 HBV vaccine doses.
“Identifying pregnant women at the greatest risk of transmitting HBV to their infants and providing these women with timely antiviral therapy prior to delivery may also help to reduce perinatal viral transmission,” Dr Schillie concluded.
1. Schillie S, Murphy TV, Fenlon N, Ko S, Ward JW. Update: Shortened Interval for Postvaccination Serologic Testing of Infants Born to Hepatitis B-Infected Mothers. MMWR Morb Mortal Wkly Rep. 2015;64(39):1118-20.
The author and interview subject have no relevant disclosures.